Advanced Signal Processing Enabled Massive MIMO With NOMA

当前无线网络的容量正在成为一个主要瓶颈，因为大部分射频带宽已经分配给特定的服务。相比之下，工作在30-300 GHz频段的毫米波(MmWave)通信是第五代(5G)及以后(B5G)无线网络的一项有前途的技术。由于其丰富的带宽和短波长，毫米波能够实现比传统微波通信(例如，低于6 GHz)更高的容量和传输速率。此外，其波长短，可以在基站中部署大量天线，并在一个小型手持设备中集成多个天线，使大规模多输入多输出(MIMO)系统与毫米波网络齐头并进。另一方面，非正交多址(NOMA)作为一种潜在的提高系统频谱和能量效率的技术，最近受到了极大的关注。NOMA允许多个用户同时接入网络和频率资源块，并根据信道状态信息(CSI)分配不同的功率电平来分离不同用户的信号。 然而，尽管使用大规模MIMO和NOMA的毫米波通信具有许多优点，但在实现如此复杂的系统方面存在技术挑战。这些要求包括需要大量的CSI，这在大规模MIMO下是很难获得的，以及天线元件的许多射频(RF)链。此外，与微波信号相比，毫米波信号具有严重的路径损耗、高的穿透损耗和恶劣的大气吸收，因此需要采用尖束定向传输来克服毫米波信号严重的路径损耗。此外，NOMA不可避免地在多个用户之间引入干扰，这些用户在相同的时间和频率共享非正交资源。在这个项目中，我们研究和开发了新的信号处理方法，以应对未来B5G网络中运行在毫米波频率的大规模MIMO-NOMA系统中的基本挑战。该提案的长期目标是为支持B5G无线通信的大规模MIMO-NOMA系统设计使能信号处理技术。短期目标包括：(1)为毫米波大规模MIMO系统设计新的信道估计技术；(2)收发信机波束形成和波束跟踪的优化；(3)NOMA用户分簇和功率分配；(4)毫米波MIMO-NOMA系统的性能评估。拟议的项目还涉及将在康科迪亚大学为本科生和研究生以及博士后研究员开展的重要培训活动。

The capacity of current wireless networks is becoming a major bottleneck as most of the radio frequency bandwidth has already been allocated for specific services. In contrast, millimeter-wave (mmWave) communication operating within the 30-300GHz frequency band is a promising technology for the 5th generation (5G) and beyond (B5G) wireless networks. Due to its abundant bandwidth and short wavelength, mmWave enables much higher capacities and transmission rates than conventional microwave communications (e.g., Sub-6 GHz). Moreover, its short wavelength allows a large number of antennas to be deployed in the base station and multiple antennas to be integrated in a small hand-held device, making massive multiple-input multiple-output (MIMO) systems go hand-in-hand with mmWave networks. On the other hand, non-orthogonal multiple access (NOMA), as a potential technology to boost system spectral and energy efficiencies, has recently received a great deal of attention. NOMA allows multiple users to access networks at the same time and frequency resource block, and separates the signals of different users by allocating different power levels according to channel state information (CSI). Despite many advantages of mmWave communication using massive MIMO and NOMA, however, there are technical challenges in implementing such a complex system. These include requiring extensive CSI, which is difficult to acquire under massive MIMO, and many radio-frequency (RF) chains for the antenna elements. Moreover, mmWave signals experience severe path loss, high penetration loss and harsh atmospheric absorption as compared to micro-wave signals, and therefore directional transmission with sharp beam is required to overcome the severe path loss of mmWave signals. In addition, NOMA inevitably introduces interferences between multiple users that share nonorthogonal resources at the same time and frequency. In this project, we investigate and develop novel signal processing approaches to tackle the fundamental challenges in massive MIMO-NOMA systems operating at mmWave frequencies for future B5G networks. The long-term objective of this proposal is to design enabling signal processing technologies for massive MIMO-NOMA systems in support of B5G wireless communications. The short-term objectives include (1) design of novel channel estimation techniques for mmWave massive MIMO systems; (2) optimization of transceiver beamforming and beam-tracking; (3) NOMA user clustering and power allocation; and (4) performance evaluation of mmWave MIMO-NOMA systems. The proposed project also involves significant training activities for both undergraduate and graduate students as well as post-doctoral research fellows that will take place at Concordia University.